Screw compressor with economizer

ABSTRACT

A screw compressor for connecting with an economizer for gas supply, includes a main body defining a compressor cavity, a male rotor and a female rotor received in the compressor cavity, a gas-vent base defining at least one gas-supply hole therein adapted for communicating with the economizer. The male rotor and the female rotor are parallel to and meshed with each other. At least the male rotor includes at least two teeth defining at least one tooth channel therebetween. The gas-supply hole is axially aligned with the at least one tooth channel to let gas from the economizer pass therethrough and enter into the at least one tooth channel along the axial direction of the male rotor.

FIELD OF THE INVENTION

The present invention relates to a screw compressor, more particularlyto a screw compressor with economizer.

BACKGROUND OF THE INVENTION

A screw compressor is one of the most common types of rotary compressorsand comprises a pair of parallel, meshed male and female rotors. Toimprove the efficiency of a compressor, an energy-saving cycle systemwith an economizer is often utilized. Please refer to FIGS. 1A-2B,refrigerating cycle Systems 100′, 100″ are illustrated. FIG. 1A is aschematic view of the refrigerating cycle system 100′ with aheat-exchange type economizer 3′. The refrigerating cycle system 100′consists of a compressor 6′ connecting with a condenser 1′, anevaporator 5′ and the heat-exchange type economizer 3′. FIG. 1B is aPressure-Enthalpy diagram of the refrigerating cycle system 100′ withthe heat-exchange type economizer 3′.

FIG. 2A is a schematic view of the refrigerating cycle system 100″ witha flash-type economizer 3″ and FIG. 2B is a Pressure-Enthalpy diagram ofthe refrigerating cycle system 100″ with the flash-type economizer 3″.The refrigerating cycle system 100″ consists of a compressor 6″connecting with a condenser 1″, an evaporator 5″ and the heat-exchangetype economizer 3″.

Please refer to FIG. 3, a gas-supply hole 10′ of an economizer of theconventional screw compressor is arranged along a radial direction tocommunicate with a tooth channel 60′ from time to time for gas supply.The tooth channel 60′ is defined by two adjacent teeth 301′, 302′ of amale rotor 30′.

FIG. 4 illustrates a gas-supply process of the conventionalradially-arranged gas-supply hole 10′ of the economizer. The rotatingangle of the rotor 30′ of the screw compressor during one gas-supplyprocess (along the arrow direction shown in FIG. 4) is the central anglecorresponding to the distance d1+a1 which the rotor end rotates along asshown in FIG. 4. d1 is the width of the gas-supply hole 10′. a1 is thedistance between teeth end spiral lines of two adjacent rotor teeth301′, 302′, corresponding to a rotation angle of the screw channel 60′.Hence, it is obvious that the rotation angle for gas supply along theradial direction is always larger than the rotation angle of the screwchannel 60′.

The disadvantages of the radially-arranged gas-supply hole 10′ of aneconomizer is: the time for a complete gas-supply process of the screwcompressor is too long, thus may cause potential backflow, and thencause a series of bad results of influencing the performances of thescrew compressor, vibration of pipes, generating high temperature atgas-supply hole area, and high noises etc.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a screwcompressor which is capable of supplying gaseous refrigerating workingmedium to a compressor cavity in shorter time for eliminating orreducing potential backflow of airflow.

In order to achieve the above-mentioned object, a screw compressoradapted for connecting with an economizer for gas supply, comprises amain body defining a compressor cavity, a male rotor and a female rotorreceived in the compressor cavity, a gas-vent base defining at least onegas-supply hole therein adapted for communicating with said economizer.The male rotor and the female rotor are parallel to and meshed with eachother. At least the male rotor comprises at least two teeth defining atleast one tooth channel therebetween. The gas-supply hole is axiallyaligned with the at least one tooth channel to let gas from theeconomizer pass therethrough and enter into the at least one toothchannel along the axial direction of the male rotor.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter, which form the subject of the claims of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1A is a schematic view of a conventional refrigerating cycle systemwith a heat-exchange type economizer;

FIG. 1B is a Pressure-Enthalpy diagram of the refrigerating cycle systemwith a heat-exchange type economizer;

FIG. 2A is a schematic view of a conventional refrigerating cycle systemwith a flash-type economizer;

FIG. 2B is a Pressure-Enthalpy diagram of the refrigerating cycle systemwith a flash-type economizer;

FIG. 3 is a view illustrating a radially-arranged gas-supply hole of aconventional economizer and a male rotor;

FIG. 4 is a schematic view illustrating a gas supply process of theconventional economizer with a radially-arranged gas-supply hole;

FIG. 5 is a view illustrating outer contour of a gas-supply hole of ascrew compressor in accordance with a first embodiment of the presentinvention;

FIG. 6 is a view illustrating outer contour of a gas-supply hole of thescrew compressor in accordance with a second embodiment of the presentinvention;

FIG. 7 is a schematic view illustrating that a tooth channel of a malerotor is separated from the gas-supply hole;

FIG. 8 is a schematic view illustrating that the tooth channel of themale rotor is going to be communicated with the gas-supply hole;

FIG. 9 is a schematic view illustrating that the tooth channel of themale rotor communicates with the gas-supply hole;

FIG. 10 is a schematic view illustrating that the tooth channel of themale rotor passes away from the gas-supply hole;

FIG. 11 is a view illustrating the rotating distance of the male rotorduring one gas supply process of an economizer of the screw compressorof the present invention;

FIG. 12 is a partially assembled view of the screw compressor inaccordance with the present invention;

FIG. 13 is a schematic view illustrating the exact location of thegas-supply hole in the screw compressor in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the present invention. However, itwill be obvious to those skilled in the art that the present inventionmay be practiced without such specific details. In other instances,well-known circuits have been shown in block diagram form in order notto obscure the present invention in unnecessary detail. For the mostpart, details concerning timing considerations and the like have beenomitted inasmuch as such details are not necessary to obtain a completeunderstanding of the present invention and are within the skills ofpersons of ordinary skill in the relevant art.

Reference will be made to the drawing figures to describe the presentinvention in detail, wherein depicted elements are not necessarily shownto scale and wherein like or similar elements are designated by same orsimilar reference numeral through the several views and same or similarterminology.

Please refer to FIGS. 12-13, a screw compressor 100 in accordance withthe present invention comprises a main body 20, a gas-vent base 50 atone end of the main body 20, a male rotor 30 and a female rotor 40parallel to and meshed with each other. Both the male rotor 30 and thefemale rotor 40 are received in the main body 20 with one end face 305thereof facing to the gas-vent base 50. The screw compressor 100 alsocomprises an economizer (not labeled) defined with at least onegas-supply hole 10 in the gas vent base 50 of the screw compressor 100.The economizer supplies gas to the screw compressor 100 along an axialdirection and through the end face 305 of the male rotor 30. In thepreferred embodiment, the screw compressor 100 is a dual-screwcompressor or a triple-screw compressor. However, it should beunderstood that in alternative embodiments, other screw compressors arealso available.

Please refer to FIG. 5, the gas-supply hole 10 in accordance with afirst embodiment of the present invention is substantially oftriple-angle and has an outer contour consistent with tooth shape, andtooth root circle of the male rotor 30. The gas-supply hole 10 comprisesopposite arc-shape first and second lateral boundaries 101, 102 and anarc-shape bottom boundary 103 connecting with the lateral boundaries101, 102. In detail, the opposite first and second lateral boundaries101, 102 of the gas-supply hole 10 anastomose with part of the twoopposite first and second lateral edges 303, 304 of the male rotor 30.Therefore, when the first lateral edge 303 of the male rotor 30 rotatesto be close to the first lateral boundary 101 to separate from thegas-supply hole 10, the majority of the first lateral boundary 101anastomoses with corresponding part of the first lateral edge 303. Whenthe second lateral edge 304 of the male rotor 30 rotates to be close tothe second lateral boundary 102 to communicate with the gas-supply hole10 for gas supply, the majority of the second lateral boundary 102anastomoses with corresponding part of the second lateral edge 304. Themajority of the bottom boundary 103 of the gas-supply hole 10anastomoses with tooth boot arc of the male rotor 30.

The gas-supply hole 10 also could have alternative shapes, such as asubstantial circle, rectangular shape, or a flat bar shape et al.according to the tooth shape of the male rotor 30. As shown in FIG. 6,the gas-supply hole 10 comprises a pair of straight-line first andsecond lateral boundaries 101, 102 and an arc-shape bottom boundary 103.

The economizer also could be equipped with a plurality of gas-supplyholes 10 defined in the gas-vent base 50 symmetrically orasymmetrically.

The gas supply process includes steps as follows:

S1) As shown in FIG. 7, one tooth channel 60 defined by two adjacentfirst and second teeth 301, 302 of the male rotor 30 separates from thegas-supply hole 10, and the gas-supply hole 10 is aligning with onetooth=301;

S2) the male rotor 30 rotates along an anticlockwise direction with thesecond lateral edge 304 of the first tooth 301 substantiallyanastomosing with the second lateral boundary 102 of the gas-supply hole10 to be ready to communicate with the gas-supply hole 10 for gas supply(as shown in FIG. 8);

S3) the male rotor 30 continues rotating along the anticlockwisedirection, and the tooth channel 60 becomes communicating with thegas-supply hole 10 until reaching the largest area for gas supply (asshown in FIG. 9);

S4) then the male rotor 30 continues rotating with the first lateraledge 303 of the second tooth 302 substantially anastomosing with thefirst lateral boundary 101 of the gas-supply hole 10, the gas supplyprocess this time finishes (as shown in FIG. 10).

S5) turning to S1 to repeat S1 to S4 until the whole gas supply processfinishes.

Please refer to FIG. 11, since the gas supply to the male rotor 30 isconducted from an end face 501 of the gas-vent base 50, that is feedinggas axially, the rotation angle a of the male rotor 30 (first angle) isalways smaller than the rotation angle a1 (second angle) of the toothchannel 60 in the condition that the area of the gas-supply hole 10 isno bigger than that of the tooth channel 60 of the male rotor 30.Compared with the conventional radially-arranged gas-supply hole 10′(the rotation angle of the male rotor 30′ is always bigger than therotation angle al of a tooth channel 60′.), the present inventionprovides gas supply in an axial direction which is capable of supplyinggas to a compressor cavity (not labeled) in the shortest time foroptimizing performances of the screw compressor 100.

In summary, the screw compressor 100 of the present invention is capableof feeding gaseous refrigerating working medium into the compressorcavity in a shorter time for eliminating or reducing potential backflow,hence optimizing the performances of the economizer artificially.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present invention have been setforth in the foregoing description, together with details of thestructure and function of the invention, the disclosure is illustrativeonly, and changes may be made in detail, especially in matters of shape,size, and arrangement of parts within the principles of the invention tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed. For example, the tongue portionis extended in its length or is arranged on a reverse side thereofopposite to the supporting side with other contacts but still holdingthe contacts with an arrangement indicated by the broad general meaningof the terms in which the appended claims are expressed.

What is claimed is:
 1. A screw compressor adapted for connecting with aneconomizer for gas supply, comprising: a main body defining a compressorcavity; a male rotor and a female rotor received in the compressorcavity, the male rotor and the female rotor meshed with each other, andat least the male rotor comprising at least two teeth defining at leastone tooth channel therebetween; a gas-vent base defining at least onegas-supply hole therein adapted for communicating with said economizer;and wherein the gas-supply hole is axially aligned with the at least onetooth channel to let gas from the economizer pass therethrough and enterinto the at least one tooth channel along the axial direction of themale rotor.
 2. The screw compressor as claimed in claim 1, wherein theouter contour of the gas-supply hole is similar to that of the tooth ofthe male rotor.
 3. The screw compressor as claimed in claim 2, whereinthe area of the gas-supply hole is no larger than that of the tooth. 4.The screw compressor as claimed in claim 1, wherein the gas-supply holerotates at a first angle, while the male rotor rotates at a second angleof the at least tooth channel, and wherein the first angle of thegas-supply hole is always smaller than the second angle of the at leastone tooth channel.
 5. The screw compressor as claimed in claim 1,wherein the gas-supply hole comprises first and second lateralboundaries and a bottom boundary connecting with the first and secondlateral boundaries, and the tooth of the male rotor comprises first andsecond lateral edges, and wherein as the male rotor rotates, the firstand second lateral boundaries of the gas-supply hole is capable ofpartially anastomosing with the first and second lateral edges of themale rotor.
 6. The screw compressor as claimed in claim 1, wherein thegas-supply hole has at least one of the shapes of triangle, circle,rectangular, flat bar.
 7. The screw compressor as claimed in claim 1,wherein the gas-vent base defines a plurality of gas-supply holestherethrough to communicate with said economizer and the at least onetooth channel of the male rotor.
 8. The screw compressor as claimed inclaim 1, wherein the screw compressor is a dual-screw compressor.
 9. Thescrew compressor as claimed in claim 1, wherein the screw compressor isa triple-screw compressor.
 10. The screw compressor as claimed in claim5, wherein the at least two teeth of the male rotor comprises a firsttooth and a second tooth, and wherein before the gas-supply holecommunicates with the at least one tooth channel, the male rotor rotatesto such a position that the second lateral boundary of the gas-supplyhole partially anastomoses with the second lateral edge of the firsttooth.
 11. The screw compressor as claimed in claim 10, wherein as thegas-supply hole is going to separate from the at least one toothchannel, the male rotor rotates to such a position that the firstlateral boundary of the gas-supply hole partially anastomoses with thefirst lateral edge of the second tooth.